Question: If $5a + 9b = 4$ and $x + y = -10$, what is $10a + 2y + 18b + 2x$ ?
$= 10a + 18b + 2x + 2y$ $= (2) \cdot (5a + 9b) + (2) \cdot (x + y)$ $= (2) \cdot (4) + (2) \cdot (-10)$ $= 8 - 20$ $= -12$